Method for securing vertebrae

ABSTRACT

A method of fixing vertebrae of a patient together at a surgical site includes the following steps: inserting a first cannula ( 10 ) into the body ( 130 ) of the patient; moving a first fastener ( 624 ) through the cannula ( 10 ) and securing the first fastener ( 624 ) to a first vertebrae ( 601 ); moving a second fastener ( 624 ) through the cannula ( 10 ) and securing the second fastener ( 624 ) to a second vertebrae ( 602 ); moving a first fixation element ( 650 ) through the cannula ( 10 ); and fixing the first fixation element ( 650 ) to the first and second fasteners ( 624 ).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.10/941,697, filed Sep. 15, 2004, which is a continuation of U.S.application Ser. No. 10/280,489, filed Oct. 25, 2002, now U.S. Pat. No.7,056,321, which is a continuation-in-part of U.S. application Ser. No.09/630,077, filed Aug. 1, 2000, now U.S. Pat. No. 6,530,926. The entiredisclosure of U.S. Pat. No. 6,530,926 and U.S. Pat. No. 7,056,321 isconsidered a part of the disclosure of this application and is herebyincorporated by reference herein.

TECHNICAL FIELD

The present invention relates to a method of fixing vertebrae of apatient together at a surgical site.

BACKGROUND OF THE INVENTION

Percutaneous surgery is a procedure in which surgical instruments and anendoscope are inserted through a cannula into the body of a patient. Aviewing element, typically a small video camera, is part of theendoscope and is connected to a monitor so that the surgeon may view thesurgical site.

The cannula is a hollow tube that is inserted through an incision intothe body of a patient so that a distal end of the cannula lies adjacentthe surgical site. The instruments, usually one at a time, and theendoscope are inserted through the cannula. The cannula also allows theinstruments and endoscope to be removed from the body and/or adjusted inthe body during the surgery without trauma to the body.

A conventional apparatus for supporting the cannula and the endoscopeallows a surgeon to manipulate the surgical instruments without alsomoving the endoscope. Also, a known support apparatus allows adjustmentof the endoscope relative to the cannula for viewing different areas ofthe surgical site in the body.

While the above described apparatus enables many types of surgeries atsmall surgical sites, the fixing of vertebrae together has heretoforebeen conducted by a much more invasive open surgical method.

SUMMARY OF THE INVENTION

In accordance with the present invention, a method of fixing vertebraeof a patient together at a surgical site includes the following steps:inserting a first cannula into the body of the patent; moving a firstfastener through the cannula and securing the first fastener to a firstvertebrae; moving a second fastener through the cannula and securing thesecond fastener to a second vertebrae; moving a first fixation elementthrough the cannula; and fixing the first fixation element to the firstand second fasteners.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features of the present invention will becomemore apparent to one skilled in the art upon consideration of thefollowing description of the invention and the accompanying drawings inwhich:

FIG. 1 is an exploded perspective view of a surgical cannula constructedfor use with the present invention, the cannula being shown in anexpanded condition.

FIG. 2 is a perspective view of the cannula of FIG. 1 with parts removedfor clarity, the cannula being shown in a contracted condition.

FIG. 3 is a schematic end view showing the cannula of FIG. 1 in theexpanded position.

FIG. 4 is a rollout view of a part of the cannula of FIG. 1.

FIG. 5 is a schematic sectional view of the cannula of FIG. 1 during asurgical procedure.

FIG. 6 is a schematic view of a support apparatus constructed for usewith the present invention.

FIG. 7 is a schematic view taken along line 7-7 in FIG. 6.

FIG. 8 is a schematic view taken along line 8-8 in FIG. 6 showing partof the support of FIG. 6.

FIG. 9 is a schematic view taken along line 9-9 in FIG. 6 showing partof the support apparatus of FIG. 6.

FIG. 10 is a schematic view taken along line 10-10 in FIG. 6 with partsremoved.

FIG. 11 is a schematic view taken along line 11-11 in FIG. 6.

FIG. 12 is a schematic view taken along line 12-12 in FIG. 6 showingpart of the support apparatus of FIG. 6.

FIG. 13 is a schematic view taken along line 13-13 in FIG. 6 showingpart of the support apparatus of FIG. 6.

FIG. 14 is a perspective view of the support apparatus of FIG. 6.

FIG. 15 is a perspective view of the support apparatus of FIG. 6 lookingat the support apparatus from an angle different than FIG. 13.

FIG. 16 is a perspective view of the support apparatus of FIG. 6 lookingat the support apparatus from an angle different than FIGS. 14 and 15.

FIG. 17 is a sectional view taken approximately along line 17-17 of FIG.9.

FIG. 18 is an enlarged view of a part of FIG. 17.

FIG. 19 is a schematic view taken along line 19-19 in FIG. 10 with partsremoved.

FIG. 20 is a view further illustrating parts shown in FIG. 10.

FIG. 21 is a view taken approximately along line 21-21 of FIG. 20.

FIG. 22 is a schematic view showing the support apparatus with anassociated known mechanical arm.

FIG. 23 is a schematic view of another feature of part of the supportapparatus of FIG. 6.

FIG. 24 is a schematic view of a fixation assembly attached to vertebraeof a patient.

FIG. 25 is a schematic view taken along line 25-25 of FIG. 24.

FIG. 26 is an exploded schematic view of part of the assembly of FIG.24.

FIG. 27 is a schematic view of another fixation assembly attached tovertebrae of a patient.

FIG. 28 is a schematic view taken along line 28-28 of FIG. 27.

FIG. 29 is an exploded schematic view of part of the assembly of FIG.27.

FIG. 30 is an exploded view of part of a cutting tool used with theclaimed method; and

FIG. 31 is an assembled view of part of the cutting tool of FIG. 30.

DESCRIPTION OF A PREFERRED

The present invention is directed to a method for fixing the vertebraeof a patient at a surgical site.

The method involves the use of a cannula, an adjustable support for thecannula, and the inserting of surgical instruments, a viewing device,and a vertebral fixation assembly through the cannula to the surgicalsite.

FIGS. 1-5 illustrate one suitable cannula 10 constructed for use in amethod in accordance with the present invention. The cannula 10 is atubular structure 12 centered on an axis 14. The tubular structure 12defines a passage 16 through the cannula 10. Surgical instruments areinserted into the body during surgery through the passage 16.

The tubular structure 12 comprises a first tubular portion 20 and asecond tubular portion 40 attached to the first tubular portion. Thefirst tubular portion 20 is preferably made of a length of stainlesssteel tubing, but could alternatively be made of another suitablematerial. The first tubular portion 20 has a proximal end 22 and adistal end 24. Parallel cylindrical inner and outer surfaces 26 and 28,respectively, extend between the ends 22, 24 of the first tubularportion 20. The inner surface 26 defines a first passage portion 30 ofthe passage 16 through the cannula 10. The first passage portion 30 hasa diameter D1 that is preferably in the range from 10 mm to 30 mm.

The second tubular portion 40 of the tubular structure 12 is attached tothe distal end 24 of the first tubular portion 20. The second tubularportion 40 is preferably made from stainless steel, but couldalternatively be made from another suitable material.

As best seen in the rollout view of FIG. 4, the second tubular portion40 comprises an arcuate segment 42 of sheet stock. The arcuate segment42 includes first and second arcuate edges 44 and 46, respectively, andfirst and second planar edges 48 and 50, respectively. The first andsecond planar edges 48 and 50 are rolled in an overlapping manner toform the tubular configuration of the second tubular portion 40.

When the second tubular portion 40 has been rolled into its tubularconfiguration, the first and second arcuate edges 44 and 46 defineoppositely disposed first and second ends 60 and 62 (FIGS. 1 and 2),respectively, of the second tubular portion. The first and second ends60 and 62 are connected by a central portion 64. The first end 60 of thesecond tubular portion 40 is attached to the distal end 24 of the firsttubular portion 20 by a single fastener, such as a rivet 66. The rivet66 extends through two aligned apertures 68 (FIG. 4) at the first end 60of the second tubular portion 40. The first end 60 of the second tubularportion 40 is pivotable about the rivet 66.

The second tubular portion 40 includes parallel inner and outer surfaces70 and 72 (FIGS. 1 and 2), respectively, extending between the first andsecond ends 60 and 62. The inner surface 70 defines a second passageportion 74 of the passage 16 through the cannula 10 that extends as acontinuation of the first passage portion 30 in the first tubularportion 20.

An arcuate slot 80 is formed in the second tubular portion 40 andextends between the inner and outer surfaces 70 and 72 of the secondtubular portion. The arcuate slot 80 extends along a curvilinear path inthe central portion 64 of the second tubular portion 40 toward thesecond end 60 of the second tubular portion. The arcuate slot 80 has afirst terminal end 82 located in the central portion 64 of the secondtubular portion 40. A second terminal end 84 of the arcuate slot 80 islocated adjacent the intersection of the second arcuate edge 46 and thefirst planar edge 48 of the arcuate segment 42.

A guide pin 90 is attached to the inner surface 70 of the second tubularportion 40 adjacent the intersection of the second arcuate edge 46 andthe second planar edge 50. In the tubular configuration of the secondtubular portion 40, the guide pin 90 is located in the arcuate slot 80and is movable along the curvilinear path of the arcuate slot. A washer92 is secured to an inner end of the guide pin 90 to retain the guidepin in the arcuate slot 80.

The second tubular portion 40 of the tubular structure 12 is expandablefrom a contracted condition shown in FIG. 2 to an expanded conditionshown in FIG. 1. In the contracted condition, the guide pin 90 islocated in the first terminal end 82 of the arcuate slot 80 in thesecond tubular portion 40 and the second passage portion 74 defined bythe second tubular portion is cylindrical in shape. The second passage74 has a generally constant diameter D2 (FIGS. 2 and 3) that isapproximately equal to the diameter D1 of the first tubular portion 20.Thus, the cross-sectional area of the second passage portion 74 at thesecond end 62 of the second tubular portion 40, which is a function ofthe diameter D2, is approximately the same as the cross-sectional areaat the first end 60 of the second tubular portion and is approximatelythe same as the cross-sectional area of the first passage portion 30 inthe first tubular portion 20.

In the expanded condition, the guide pin 90 is located in the secondterminal end 84 of the arcuate slot 80 in the second tubular portion 40and the second tubular portion has a conical configuration. At thesecond end 62 of the second tubular portion 40, the second passageportion 74 has a diameter D3 (FIG. 3) that is larger than the diameterD2 of the second passage portion at the first end 60. Preferably, thediameter D3 of the second passage portion 74 at the second end 62 of thesecond tubular portion 40 is 40% to 80% greater than the diameter D2 ofthe second passage portion at the first end 60. Thus, in the expandedcondition, the cross-sectional area of the second passage portion 74 atthe second end 62 of the second tubular portion 40, which is a functionof the diameter D3, is 16% to 64% greater than the cross-sectional areaof the second passage portion at the first end 60 of the second tubularportion. In the expanded condition, the cross-sectional area of thesecond passage portion 74 at the second end 62 of the second tubularportion 40 is large enough to overlie a major portion of at least twoadjacent vertebrae.

The cannula 10 includes an outer layer 100 (FIG. 1) for maintaining thesecond tubular portion 40 of the cannula in the contracted condition. Itis contemplated that other suitable means for maintaining the secondtubular portion 40 in the contracted condition could be employed. Inaccordance with a preferred embodiment of the present invention, theouter layer 100 comprises a section of plastic tubing 102 which is heatshrunk over both the first and second tubular portions 20 and 40 to holdthe second tubular portion in the contracted condition.

In addition, a loop of polyester string 104 for tearing the heat shrinktubing 102 is wrapped around the heat shrink tubing so that it extendsboth underneath and on top of the tubing. An outer end 106 of the string104 extends beyond the tubing 102.

FIG. 1 shows an actuatable device 111 for expanding the second tubularportion 40 from the contracted condition to the expanded condition. Inaccordance with a preferred embodiment of the present invention, theactuatable device 111 comprises a manually operated expansion tool 112.The expansion tool 112 resembles a common pair of scissors and has apair of legs 114 pivotally connected to one another. The expansion tool112 includes a frustoconical end section 116 formed by a pair offrustoconical halves 118. Each of the frustoconical halves 118 extendsfrom a respective one of the legs 114 of the expansion tool 112. It iscontemplated that other suitable means for expanding the second tubularportion 40 toward the expanded condition could be employed, such as aninflatable balloon (not shown).

During an endoscopic surgical procedure, the cannula 10 is inserted intothe body of a patient in the concreted condition. The outer end 106 ofthe string 104 is then manually pulled on by the surgeon. Pulling on thestring 104 tears the heat shrink tubing 102 most of the way along theheat shrink tubing, which frees the second tubular portion 40 forexpansion. The heat shrink tubing 102, in its torn condition, remainsattached or secured to the first tubular portion 20.

Next, the expansion tool 112 is inserted into the passage 16 in thecannula 10 until the frustoconical end section 114 is located at thesecond end 62 of the second tubular portion 40. The legs 118 of theexpansion tool 112 are manually separated, causing the frustoconicalhalves 118 to separate also. As the halves 118 separate, a radiallyoutwardly directed force is exerted on the inner surface 70 of thesecond tubular portion 40 by the halves 118, causing the second tubularportion to expand toward an expanded condition (FIG. 2C). Under theforce of the expanding expansion tool 112, the guide pin 90 slides fromthe first terminal end 82 of the arcuate slot 80 toward the secondterminal end 84 of the arcuate slot to permit the expansion of thesecond tubular portion 40. The expansion tool 112 can be rotated aboutthe axis 14 to ensure that the second tubular portion 40 of the cannula10 is completely expanded to the expanded condition. The expansion tool112 is then collapsed and removed so that one or more surgicalinstruments (indicated schematically at 21 in FIG. 5) and a viewingelement can be received through the cannula 10 and inserted into apatient's body 130. The expandable second tubular portion 40 of thecannula 10 provides a significantly larger working area for the surgeoninside the body 130 within the confines of the cannula.

The expanded tubular portion 40 can dilate and locally retract andseparate spinalis muscle and soft tissues from the vertebrae therebycreating an endoscopic operating field at the surgical site. Thisendoscopic operating field within the spinal muscles differs fromarthroscopic, laparoscopic, or cystoscopic working spaces in that thereis no physiologic space or defined tissue plane that can be insufflatedwith air or distended with fluid.

FIGS. 6-23 illustrate one suitable support apparatus for use in a methodin accordance with the present invention. The support apparatus 110includes a first support 120, a second support 140, a first adjustmentmechanism 160, a second adjustment mechanism 180, and a third adjustmentmechanism 900.

As viewed in FIGS. 2 and 17, the first support 120 is associated withthe cannula 10 and has a circular perimeter 121. The perimeter 121 has acenter 122 located on the axis 14. The first support 120 comprises acircular platform, or disk 124, which has a circular opening 126 in thecentral area of the disk 124 for receiving the proximal end 22 of thecannula 10. The circular opening 126 has a center located on the axis14. The proximal end 22 of the cannula 10 can be easily inserted intoand removed from the opening 126. The disk 124 has a projection portion120 a, which is located adjacent the perimeter 121 of the disk 124. Thedisk 124 has an upper circular surface area 124 a, which surrounds theopening 126.

As viewed in FIG. 10, the second support 140 supports a viewing device200 including a camera head 201 and an endoscope 202 with a rod and lensassembly 203, herein referred to as a viewing element, extending downthrough the passage 16 of the cannula 10. The second support 140includes a body 142 having an opening 144 through which the viewingdevice 200 extends and a clamp 146 for clamping the viewing device 200to the body 142 in the opening 144. The clamp 146 includes a threadedset screw 148 for securing the viewing device 200 to the body 142. Theset screw 148 has a manually rotatable knob 148 a and a stem threadedinto the body 142. When rotated, the screw 148 moves axially relative tothe body 142 to clamp or release the viewing device 200 depending on thedirection of rotation of the screw 148.

The body 142 of the second support 140 further includes two extensionarms 151, 152 (FIG. 8) for supporting the endoscope 202. Each extensionarm 151, 152 includes a threaded bore for receiving a resilient detentmember, or ball plunger 400.

As viewed in FIGS. 17 and 18, a ball plunger 400 is illustrated atanother location in the support apparatus 110. Each ball plunger 400,including those in the extension arms 151, 152, has an externallythreaded tubular body 402 with a cylindrical cavity 404 located therein.The cavity 404 houses a projection 406 and a coiled spring 408. Theprojections 406 of the two ball plungers 400 of the extension arms 151,152 are spherical detent members 420 in the form of balls (not shown).The spring 408 urges each projection 406 against a lip portion 409 ofthe body 402. The lip portion 409 is located at one end of the cavity404. As shown in FIG. 18, the other ball plungers 400 of the apparatus10 have projections 406 with hemispherical extensions 420 and shoulderportions 422.

As viewed in FIG. 15, the endoscope 202 has corresponding hemisphericalrecesses (not shown) for receiving the spherical detent members (balls)of the ball plungers 400 which are located in extension arms 151, 152.The springs 408 will compress in each ball plunger 400 in each extensionarm 151, 152 and the spherical detent members will move inward of eachcavity 404 and then spring back into the hemispherical recesses in theendoscope 202, as the endoscope 202 is inserted between the extensionarms 151, 152. The entire viewing device 200 will thus be securedbetween the extension arms 151, 152, but may be removed by overcomingthe force of the spherical detent members of each ball plunger 400 inthe extension arms 151, 152.

The ball plunger 400 further includes a head portion 430 with a slot 432for engaging a tool, such as a screwdriver. The ball plunger 400 may bethreadedly adjusted within the threaded bore of either extension arm151, 152 to alter the distance that the spherical detent member 420projects away from the extension arms 151, 152 (toward each other). Thisdistance, along with the stiffness of each spring 408, will determinethe holding force by which the endoscope 202 is secured between theextension arms 151, 152.

The first adjustment mechanism 160 provides for relative axialadjustment of the cannula 10 and the first support 120 along the axis14. The first adjustment mechanism 160 includes a first toothed rackmember 162, a cannula gripper mechanism 164 fixedly connected to thefirst rack member 162, a first manually adjustable, rotatable knob 166rotatably carried by the projection portion 120 a of the first support120, and a first gear member 165 (FIG. 12) rotatable by the first knob166 and in meshing engagement with the teeth 163 of the first rackmember 162. The first support 120 and, in particular, the projectionportion 120 a, rotatably carries the first gear member 165 (FIG. 12).The first rack member 162 is secured to slide axially within the firstsupport 120 and the projection portion 120 a by two ball plungers 400(FIG. 12). One ball plunger 400 is tangentially threaded into a tapered,threaded bore (FIG. 7) in the perimeter 121 of the first support 120 andthe other is tangentially threaded into a threaded bore in theprojection portion 120 a. The hemispherical extensions 420 thusfrictionally engage a smooth portion (without teeth 163) of the firstrack member 162 and bias the first rack member 162 against the firstsupport 120 and the projection portion 120 a. This biasing alsomaintains the engagement of the first rack member 162 and the first gearmember 165 (FIG. 12).

As viewed in FIGS. 10 and 19, the cannula gripper mechanism 164 includestwo gripper arms 172, 174 for clamping against the outer surface of thecannula 10, and a gripper actuating lever 176 for moving the arms 172,174 into engagement with the outer surface of the cannula 10 and forreleasing the arms 172, 174 from engagement with the cannula 10.

As viewed in FIG. 19, the cannula gripper mechanism 164 further includesa support pin 177, a coiled spring 188, a washer 189 with a bore (notshown), and a lock pin 190. The support pin 177 has a head 179, a shaft180, and an oblong, or flat, end 181 that can mate with the bore in thewasher 189. Other suitable structures could be used.

During assembly, the coiled spring 188 is interposed between the arms172, 174. The flat end 181 of the support pin 177 is inserted through acircular bore in the first clamp arm 172, through the coil of the spring188, through a circular bore in the second arm 174, and through the borein the washer 189. The flat end 181 of the support pin 177 is theninserted into a slot 176 a in the lever 176. The lock pin 190 isinserted through a bore in the lever 176 and through a bore in the flatend 181 of the support pin 177 thereby securing the mechanism 164together and allowing the lever 176 to rotate about the lock pin 190. Acamming surface 178 on the lever 176 adjacent the washer 189 forces thearms 172, 174 together to grip the cannula 10 as the lever 176 isrotated clockwise (as viewed in FIG. 10). Counterclockwise rotation ofthe lever 176 allows the spring 188 to force the arms 172, 174 apart andreleases the cannula 10 from the gripper mechanism 164.

When the gripper mechanism 164 is either gripping the cannula 10 orreleased from the cannula 10 and the knob 166 is rotated, the disk 124and parts attached to the disk 124 will move along the axis 14 of thecannula 10 relative to the cannula 10. After the support apparatus 110is initially lined up with the cannula 10. The viewing device 200 may bepositioned on the support apparatus 110 and adjusted along the axis 14by rotation of knob 166.

The second adjustment mechanism 180 provides axial adjustment of thefirst and second supports 20, 40 relative to each other along the axis14. The second adjustment mechanism 180 includes a second toothed rackmember 182 connected to the first support 120, a second manuallyadjustable, rotatable knob 186 rotatably carried by the body 142 of thesecond support 140, and a second toothed gear member 185 (FIG. 13)rotatable by the second knob 186 and in meshing engagement with theteeth 183 of the second rack member 182. The second support 140, and inparticular, the body 142, rotatably carries the second gear member 185(FIG. 13).

The body 142 of the second support 140 may have a notch 149 which canfit around part 902 a of the third adjustment mechanism 900 and allowthe lower surface of the body 142 to completely abut the disk 124 as thebody 142 is brought into an axial position adjacent the disk 124.

The second rack member 182 is secured to slide axially within the secondsupport 140 by a ball plunger 400 (FIG. 13). The ball plunger 400 istangentially threaded into a threaded bore in the side of the notch 149of the second support 140. The hemispherical extension 420 thusfrictionally engages a smooth portion (without teeth 183) of the secondrack member 182 and biases the second rack member 182 against the secondsupport 140. The biasing also maintains the engagement of the secondrack member 182 and the second gear member 185. Both sides of the notch149 have tapered portions 149 a, 149 b for facilitating insertion of theball plunger 400 into the threaded bore of the notch 149 of the secondsupport 140. Rotation of the knob 186 causes the body 142 and theviewing device 200 attached thereto to move relative to the cannula 10and disk 124 along the axis 14.

The third adjustment mechanism 900 provides arcuate, circumferentialadjustment of the second support 140 about the axis 14 relative to thefirst support 120. The third adjustment mechanism 900 includes awedge-shaped support member 902 (FIG. 9) fixedly connecting the secondrack member 182 to a ring member 904 that is rotatably supported by thefirst support 120 and rotatable about the axis 14 relative to the firstsupport 120 (FIG. 17).

The third adjustment mechanism 900 further includes a third manuallyadjustable, rotatable knob 906 that is part of a set screw. The setscrew is rotatably threaded into a projection portion 902 a of thesupport member 902 and is engageable with the circular perimeter 121 ofthe disk 124 of the first support 120 to lock the support member 902 inan arcuate position relative to the first support 120 and the axis 14.

As viewed in FIGS. 17 and 18, the ring member 904 is supported within acylindrical, open ended recess 905 of the first support 120. The recess905 is concentric about the axis 14. The perimeter 904 a of the ringmember 904 has a groove 904 b for engaging a plurality of ball plungers400 (preferably four equally spaced apart) in the first support 120.Each of these ball plungers 400 is similar in construction. Each ballplunger 400 is threaded radially into the perimeter 121 of the firstsupport 120 to provide a hemispherical extension 420 extending into therecess 905 of the first support 120.

The ring member 904 thus is biasingly supported within the recess 905 ofthe first support 120 and can rotatably slide within the recess 905about the axis 14. The ball plungers 400 operatively support the ringmember 904 in the recess 905 of the first support 120. The ring member904, along with the second support 140 and the second and thirdadjustment mechanisms 180, 900, can be easily removed from the recess905 for cleaning, maintenance, etc. of the parts by overcoming the forceapplied by the ball plungers 400 to the ring member 904. When the knob906 is rotated to disengage the perimeter 121 of disk 124, the body 142and parts connected thereto can be manually rotated about the axis 14.This causes the viewing device 200 to rotate about the axis 14 of thecannula 10 and enables the surgeon to view different parts of thesurgical sight as desired.

As viewed in FIG. 16, the fixed connections of the first rack member 162to a support arm 300, the second rack member 182 to the wedge-shapedsupport member 902, and the support member 902 to the ring member 904may be made by one or more suitable metal fasteners 290, such as rivetsor bolts. The entire support apparatus 110 can be constructed from metalor any other suitable material having sufficient mechanical strength anddurability. Certain parts may be made from materials permitting X-raysand other techniques for viewing the surgical sight (i.e., radiolucentparts). Other parts may also be made from non-magnetic materials toreduce electromagnetic interference (i.e., electromagnetic insulatingparts).

As viewed in FIGS. 20-22, the gripper's arms 172, 174 are a part of thesupport arm 300 for attaching the support apparatus 110 to a mechanicalrobotic arm 301. The support arm 300 includes an arm portion 302 that isformed integrally with the arms 172, 174. The arms 172, 174 areintegrally constructed with the arm portion 302.

The support arm 300 also includes an arm portion 303. The arm portion303 has an attaching structure 304, including a groove 305, which snapsinto a socket in the mechanical arm 301. Detents of any suitable typeand designated 306 in the mechanical arm 301, hold the arm portion 303in position in the socket in the mechanical arm 301. The detents 306 maybe controlled by external actuation levers (not shown) on the mechanicalarm 301 for manually releasing the arm portion 303 from the mechanicalarm 301.

The arm portions 302 and 303 are pivotally connected to each other by afastener 310. The fastener 310 extends through an opening 311 in the armportion 302 and threads into a threaded opening 312 in the arm portion303. When the fastener 310 is released, the arm portions 302, 303 maypivot relative to each other about a pivot axis 314. The pivot axis 314is centered on the axis of the fastener 310 and the axis of the threadedopening 312. When the fastener 310 is tightly screwed into the threadedopening 312, the arm portions 302, 303 are secured together againstpivoting movement. When the fastener is released, the arm portions 303,302 may pivot relative to each other about the axis 314.

The end of the arm portion 302, which is adjacent to the arm portion303, has a convex surface 350, which is curved about the axis 314. Thearm portion 303 has a concave surface 351, which is also curved aboutthe axis 314. The surfaces 350, 351 move concentrically relative to eachother when the arm portions 303 and 302 pivot relatively about the axis314.

The arm portion 303 has a set of teeth 320 which encircle the axis 314and which project axially toward a set of teeth 321 on the arm portion302. The teeth 321 project axially toward the teeth 320. The teeth 320and the teeth 321 mesh with each other and provide a locking action sothat the arm portions 302, 303 are positively locked against relativemovement about axis 314 when the fastener 310 is tightly screwed intothe opening 312. The teeth 320, 321 comprise a lock which blocksrelative rotation of the arm portions 302, 303 about the axis 314. Whenthe fastener 310 is loosened, the arm portions 302, 303 may be rotatedrelative to each other about the axis 314, and thus, the arm portions302, 303 may pivot relative to each other to adjust the position of thesupport apparatus 110.

A cylindrical projection 325 is welded to the arm portion 303. Thus, theprojection 325 and arm portion 303 are fixedly connected together. Theprojection 325 is centered on the axis 314 and contains a chamber 328.

As viewed in FIG. 22, the chamber 328 communicates with a fluid passage329 in a male fluid connector 331. The male connector 331 attaches to amale connector 333 on the mechanical arm 301 by means of a flexible hose392 so that the fluid passage 329 communicates with a fluid passage inthe mechanical arm 301.

As viewed in FIG. 20, the chamber 328 is closed at its upper end by acap 335. The cap 335 has an opening 336 centered on the axis 314. Theopening 336 communicates with the chamber 328. A manually movableinternal valve member 340 normally closes the opening and blocks thechamber 328 from communicating with the ambient air surrounding thesupport arm 300. The valve member 340 is connected to a stem 341, whichis also centered on the axis 314. The stem 341 has a knob or button 343on its end that may be manually depressed to move the stem 341 and valvemember 340 downward into the chamber 328. When the stem 341 and valvemember 340 are so moved, the chamber 328 is in communication with theambient air surrounding the device due to the unblocking of the opening336.

The mechanical arm 301 is a known device and is of the type generallydisclosed in U.S. Pat. No. 4,863,133. The mechanical arm 301 is sold byLeonard Medical, Inc. 1464 Holcomb Road, Huntington Valley, Pa., 19006.The mechanical arm 301 includes relatively movable parts, which permitmovement and adjustment of the support apparatus 110 in a variety inplanes, directions, and orientations. The mechanical arm 301 permitseasy movement when a vacuum is not applied to the arm 301. When a vacuumis applied to the arm 301, relative movement of the parts of the arm 301is resisted, and therefore adjustment of the support apparatus 110 isdifficult.

When the button 343 is depressed, the chamber 328 loses its vacuum andthe pressure in the chamber 328 increases toward ambient pressure. Thepassage 329 communicates this pressure increase to the mechanical arm301, and thus the parts of the mechanical arm 301 are free to move andallow for adjustment of the position of the support apparatus 110 by thesurgeon.

Accordingly, when the surgeon uses the support apparatus 110, thesupport arm 300 is snapped into the socket of the mechanical arm 301where it is held by the detent 306. The surgeon may then depress thebutton 343 and relatively move parts of the mechanical arm 301, as wellas the support apparatus 110 into the position where the surgeon desiresthe support apparatus 110 to be. This position may be where the opening126 in the disk 124 is aligned with the proximal end 16 of the cannula10 that has been positioned in the patient's body with the distal end 24of the cannula 10 being located in an incision in the body of thepatient. The viewing device 200 may be mounted on the support apparatus110, and the surgeon may make adjustments prior to and during thesurgical procedure as desired, as described above.

As viewed in FIG. 23, the support apparatus 110 may include a secondsupport with a fourth adjustment mechanism 500 for rotating the viewingdevice 200 about an axis 501 (FIG. 15) defined by the ball plungers 400of the extension arms 151, 152 when set screw 148 is not clamping theviewing device 200 to the body 142. The axis 501 is offset from the axis14 of the cannula 10 and perpendicular to the axis 14 of the cannula 10.Rotation of the viewing device 200 about axis 501 causes the endoscope200 and the rod and lens assembly 203 to move perpendicular to the axis14 of the cannula 10. This rotation will result in radial adjustment ofthe position of the rod and lens assembly 203 in a radial directiontransverse to the axis 14.

The spring-loaded connections of the spherical detent members 420 of theball plungers 400 and the hemispherical recesses of the endoscope 202allow rotation about the axis 501 when the set screw 148 is releasedfrom clamping engagement of the viewing device 200.

The mechanism 500 includes a threaded bore 510 in the second support 140and an adjustable member 520 for moving (vertically as viewed in theFIGS.) a part of the viewing device 200 about the axis 501. Theadjustable member 520 has a rounded first end portion 522, a threadedmiddle portion 524, and a knurled second end portion 526, or knob. Thebore 510 extends at an angle as shown in FIG. 23 from a lower portion ofthe second support 140 up to the opening 144 in the clamp 146 of thesecond support 140.

The adjustable member 520 is rotated and threaded into the bore 510 andmay be rotated until the first end portion 522 protrudes into theopening 144 of the second support 140. Accordingly, when the surgeonwishes to adjust the rod and lens assembly 203 (within the surgicalsight) about the axis 501 and radially relative to the axis 14 of thecannula 10, the surgeon may loosen the connection of the set screw 148with the viewing device 200 and rotate the adjustable member 520 bymanually rotating knob 526 so that the first end portion 522 verticallyextends farther or less into the opening 144. This adjustment willadjust the part of the viewing device 200 engaged by the clamp 146 alongthe axis 14, rotate the viewing device 200 about the axis 501, and causethe lens 203 at the surgical site to move transverse to the axis 14 ofthe cannula 10. This will expand the area of the surgical site that thesurgeon may view. When the adjustment is complete, the surgeon maytighten the set screw 148 and re-secure the viewing device 200 to thesecond support 140 of the support apparatus 110.

The method of securing two vertebrae 601, 602 together in accordancewith the present invention may include the insertion of a vertebralfixation assembly 620 through the cannula 10 and attachment of thevertebral fixation assembly 620 to two vertebrae (such as the L4 and L5vertebrae), as viewed in FIGS. 24-29. The fixation assembly 620 may beof any suitable construction and is shown in FIG. 26 as including fouridentical attachment devices 622. Each attachment device 622 includes athreaded fastener 624 or pedicle screw, placed in a vertebra 601 or 602,as viewed in FIGS. 25 & 28. The fastener 624, has a first threadedportion 626 with a first threaded diameter that threads into thevertebrae 601, 602 by screwing the fastener 624 into the vertebrae. Thefastener 624 further includes a second threaded portion 628 with asecond threaded diameter that may be less than the first threadeddiameter. The second threaded portion 628 extends away from thevertebrae 601, 602.

A first hexagonal engagement surface 630, intermediate the first andsecond threaded portions 626, 628, allows gripping of the fastener 624when the fastener is screwed into the vertebrae 601, 602. A first convexengagement surface 632, adjacent the first hexagonal engagement surface630 and the second threaded portion 628, projects away from thevertebrae 601, 602. A second hexagonal engagement surface 634 projectsaway from the second threaded portion 628 and allows further gripping ofthe fastener 624.

Each attachment device 622 further includes a first fixation washer 640(FIGS. 26 & 29) that engages the first convex engagement surface 632.The first fixation washer 640 includes a first concave engagementsurface 642 for abutting and slidingly engaging the first convexengagement surface 632 of the fastener 624.

The first fixation washer 640 further includes spikes 644, typicallythree, extending away from the vertebrae 601, 602. The spikes 644 of thefirst fixation washer 640 engage a lower knurled surface 652 of avertebral fixation element 650 that in FIGS. 24-26 is a spine plate.

An upper knurled surface 654 of the fixation element 650 engages thespikes 664 of a second fixation washer 660 that is identical to thefirst fixation washer 640, but inverted, as viewed in FIGS. 26 & 29. Asecond convex engagement surface 672 of a threaded locking nut 670 abutsand slidingly engages the second concave engagement surface 662 of thesecond fixation washer 660 when the locking nut 670 is loosely threadedonto the second threaded portion 628 of the fastener 624.

The convex and concave engagement surfaces 632, 642, 662, 672 allowangular adjustment of the fixation elements 650, before the locking nut670 is fully tightened, when the fasteners 624 are not threaded into thevertebrae 601, 602 exactly parallel to each other, as shown exaggeratedin FIG. 25. These surfaces may typically allow for up to a 12-degreeoffset of the axes of the two fasteners 624.

One of two types of fixation elements 650 may typically be used tosecure the vertebrae 601, 602 together. The first type may be a spinalplate 651 (FIG. 26) with two slots 653, 655 extending along thelongitudinal axis 657 of the spinal plate. The second threaded portion628 of one fastener 624, screwed into one vertebra 601, extends throughone slot 653 and the second threaded portion 628 of another fastener624, screwed into another vertebra 602, extends through the other largerslot 655. Two of the spinal plates 651, one on each side of thevertebrae 601, 602, are used to secure the two vertebrae together, asviewed in FIG. 24. The slots 653, 655 allow further transverseadjustment so that the same spinal plate 651 may be used for differentsize patients.

A second type of fixation element 650 may be two universal side blocks651 a (FIG. 29), each with one slot 653 a extending along thelongitudinal axis 657 a of each side block and a securement opening 655a extending substantially perpendicularly to each slot 653 a, as viewedin FIG. 29. The second threaded portion 628 of a fastener 624, screwedinto one vertebra 601, extends through one slot 653 a and the secondthreaded portion 628 of another fastener 624, screwed into anothervertebrae 602, extends through a slot 653 a in an identical side block651 a. The side blocks 651 a further include lower and upper knurledsurfaces 652 a, 654 a similar to the knurled surfaces 652, 654 of thespinal plate 651.

This second type of fixation element 650 further includes a rod 658 aextending from the opening 655 a in one side block 651 a to the opening655 a in the other side block 651 a. Set screws 659 a secure the rod 658a in each opening 655 a when the rod 658 a is positioned properly tosecure the vertebrae 601, 602 together, as viewed in FIG. 27.

Four of the side blocks 651 a, one on each side of each vertebra 601,602, and two rods 658 a are used to secure the two vertebrae together.The slots 653 a allow further transverse adjustment so that the sameside block 651 a may be used for different size patients. The rods 658 amay also be cut to fit different sized patients.

The cannula 10, support apparatus 110, and vertebral fixation assembly620 described above may be used to perform an operation which securestwo vertebrae 601, 602 together, such as the posterolateral fusion andscrew placement described above. This type of operation traditionallyresults in much blood loss because of the open access to the spinerequired for its performance. Utilizing the cannula 10 and supportapparatus 110 for placement of the fixation assembly 620 at the surgicalsite and attachment of the fixation assembly 620 to the vertebrae 601,602 in a manner to be described results in a much less invasiveprocedure and significantly less blood loss.

In accordance with the present invention, a method of fixing thevertebrae 601, 602 of a patient together at two surgical sites includestwo main procedures. The first procedure includes the following steps:inserting a first cannula 10 into the body 130 of the patient adjacentone side of the spinal column; inserting a second cannula 10 into thebody 130 of the patient adjacent the other side of the spinal column;expanding the second tubular portions 40 of both cannulae as describedabove thereby creating a substantially complete view of both sides ofthe two adjacent vertebrae 601, 602 utilizing two endoscopes 200 and oneor more monitors.

Alternatively, instead of using two cannulae and two endoscopessimultaneously so that both sides of adjacent vertebrae may be worked onby the surgeon at the same time, only one side of the adjacent vertebraemay be worked on and then the other side of the adjacent vertebrae maybe worked on. In this case, only one endoscope, one endoscope support110, and one monitor is required. Two cannulae would most probably beused, one for each side of the vertebrae.

The second procedure includes accessing the vertebrae 601, 602 throughthe cannulae 10; drilling four insertion openings, one in each side ofeach vertebra 601, 602 utilizing suitable instruments extending throughthe cannula 10; inserting fasteners 624 through each cannulae andscrewing one fastener into each insertion opening thereby securing eachfastener 624 to a vertebra; checking the position of the vertebrae toensure that the vertebrae have maintained the proper position and, ifnecessary, repositioning the vertebrae; moving eight fixation washers640, 660, four locking nuts 670, and two fixation elements 650 throughthe cannulae; placing four fixation washers 640 and the fixationelements on the fasteners, each fastener extending through one fixationwasher and one slot in each fixation element; placing the additionalfixation washers 660 on the fasteners; and threading the locking nutsonto each fastener thereby fixing the fixation elements to the vertebraeand securing the vertebrae together in a natural and permanent positionwithin the body. Also, bone graft may be moved through the cannula 10and placed in and around the fixation element 650 and fasteners 624 topermit a posterior fusion across the bony elements of the vertebrae 601,602.

If necessary, the disk between the vertebrae 601, 602 may be removedthrough the cannula; the area between the vertebrae cleaned and thevertebrae prepared for receiving a fusion cage or cages and/or diskreplacement material. This would be done before inserting the fasteners624 or attaching the fixation elements 650. The method may also includeinserting, through the cannulae 10, one or more appropriately sizedfusion cages and positioning the fusion cage(s) appropriately relativeto the vertebrae 601, 602; and inserting bone graft tissue through thecannulae 10 and positioning the tissue in and around the fusion cage(s).

The fusion cage may be of any known construction. One typical fusioncage is a hollow rectangular cage that is inserted into grooves that areformed in facing bone surfaces of the vertebrae. Another type of fusioncage is a hollow cylindrical threaded cage which screws into positionbetween the vertebrae. Any suitable fusion cage may be used.

The cannulae 10 and the shrink wrap 102 are then removed from the bodyand the incisions are suitably closed. After a time, vertebrae 601, 602and bone graft will grow together across the fusion cage(s) and in andaround the fixation elements 650. The vertebrae 601, 602 will then nolonger require the fixation assembly to maintain their position. Thefixation elements 650 and fasteners 624 may then be removed. The removalprocedure may utilize the same type of apparatus as was used in thefirst and second procedures (i.e., cannula, support apparatus, etc.).

The first and second cannulae 10 may be shifted slightly in theincisions in the body 130 to desired locations within the incisions atany time during the first and second procedures or the removalprocedure. This is accomplished by changing the position of the supportapparatus 110 by manipulating the arm 301.

The method described above may, and most probably does, involve removalof tissue from the surgical site through the cannula 10. Muscle, fat,and bone may be removed through the cannula 10 to provide a proper viewof the vertebrae 601, 602 and the location to receive the fixationassembly 620. Different tools may be used in the process of removingtissue. These tools may include a burr and/or tissue cutting blades thatare inserted through the cannula 10.

A preferred tissue cutting blade device 710 is shown in FIGS. 30-31. Thedevice 710 has an axis 712 and includes inner and outer cutting tubes740, 750. Each of the inner and outer tubes 740, 750 has openings 741,751 into their interiors. Cutting teeth 745, 755 are located on oppositesides of each opening 741, 751.

The inner tube 740 rotates about the axis 712 relative to the outer tube750 within the outer tube. The inner tube 740 rotates in oppositedirections a predetermined amount equal to one or more revolutions aboutthe axis 712, then rotates in the opposite direction the samepredetermined amount. Thus, the inner tube 740 oscillates about the axis712. As the inner tube 740 oscillates/rotates about the axis 712, thecutting teeth 745, 755 on the inner and outer tubes 740, 750 cut tissue.Alternatively, the inner tube 740 may rotate in one direction (clockwiseor counterclockwise) within the outer tube.

During the cutting of tissue, a saline solution or the like may beforced through the annular space 770 between the inner tube 740 and theouter tube 750 to the surgical site. Suction may be applied in theopening 741 of the inner tube 740 to remove the cut tissue and thesaline solution from the surgical site.

A tubular sheath 760 receives the inner and outer cutting tubes 740,750. The sheath 760 extends along the length of the cutting tubes 740,750 and adjacent a distal end of the cutting tubes where the cuttingteeth 745, 755 are located. The sheath 760 is a stainless steel tubethat is electrically insulated along its length from the patient's bodyand from the outer tube 750. An electrical insulator 763, such as asuitable polymer coating, is provided over the outside and insidesurfaces of the sheath 760. However, a selected area 762 of the outsidesurface of the sheath 760 adjacent the distal end of the cutting tubes740, 750 is not coated with the insulator 763. A portion 765 of thedistal end of the sheath 760 is cut away so that the cutting teeth 745,755 on the cutting tubes 740, 750 are not blocked by the sheath 760 fromcutting tissue.

An electric current from a current source 766 is applied to the sheath760. The electric current flows through the sheath 760 and to theselected uncoated area 762 of the sheath. The current then flows throughtissue and blood into the distal end of the outer cutting tube 750 andback to the current source through the outer cutting tube to form acompleted circuit.

The current flow through the electrically energized sheath 760 and outercutting tube 750 serves to electrocoagulate blood in the cutting area atthe surgical site. Electrocoagulation of blood is known and any othersuitable electrocoagulation device may alternatively be used.

From the above description, one skilled in the art should realize thatviewing of the surgical site may be performed without using anendoscope. A microscope or glasses that magnify the site may be used. Infact, any suitable viewing device may be used. Also, the procedurediscussed above mentions drilling the vertebrae. Any suitablealternative to drilling may be used such as using an awl or otherinstrument to form an opening to receive a fastener.

Also, from the above description of the invention, those skilled in theart will perceive improvements, changes and modifications. Suchimprovements, changes and modifications within the skill of the art areintended to be covered by the appended claims.

What is claimed:
 1. A minimally invasive method of fixing first andsecond vertebrae of a patient together at a surgical site, the methodcomprising: providing fixation elements including at least first andsecond fasteners configured to be secured to the first and secondvertebrae, respectively, and a plate configured to connect the first andsecond fasteners; inserting an access device to the surgical site;removing at least a portion of a disk from between the first and secondvertebrae through the access device; inserting at least one implantthrough the access device and positioning the at least one implantbetween the first and second vertebrae; inserting the first and secondfasteners through the access device to the surgical site and securingthe first and second fasteners to the first and second vertebrae,respectively; inserting the plate through the access device andpositioning the plate with the first and second fasteners extendingthrough openings in the plate; and inserting first and second nutsthrough the access device and threading the nuts onto the first andsecond fasteners, such that the first and second fasteners are securedto the first and second vertebrae, respectively, and the plate connectsthe first and second fasteners.
 2. The method of claim 1, furtherincluding a step of filing the at least one implant with bone graftmaterial.
 3. The method of claim 1, wherein after the step of insertingthe access device to the surgical site, the method further includes astep of expanding the access device to provide access to the surgicalsite.
 4. The method of claim 3, wherein the step of expanding the accessdevice includes expanding a distal portion of the access device, whereinthe distal portion resides within the patient's body.
 5. The method ofclaim 1, wherein the first and second fasteners are bone screws.
 6. Asystem for fixing adjacent vertebrae of a patient comprising: an accessdevice adapted to define a passage from a location outside of thepatient to a location at or near the spine of the patient, the accessdevice being at least partially actuatable between a first configurationand a second configuration, wherein the passage of the access device inthe second configuration has a cross-sectional area at a first locationthat is greater than the cross-sectional area of said passage at asecond location, wherein the first location is distal to the secondlocation; at least first and second fixation elements configured to bepassed through the access device and to be secured to at least first andsecond vertebrae, respectively, through the access device; a plateconfigured to be passed through the access device and to be fastened tothe at least first and second fixation elements after the fixationelements are secured to vertebrae, through the access device; and atleast one implant configured to be inserted between the first and secondvertebrae.
 7. The system of claim 6, wherein the plate has a pluralityof openings, each opening configured to receive at least a portion ofone of the fixation elements.
 8. The system of claim 7, furthercomprising at least first and second securing members configured tosecure the plate to the at least first and second fixation elements. 9.The system of claim 8, wherein the fixation elements are screws and thesecuring members are nuts.